97 explorer 4.0 overheating coolant loss please help

[Callmejohn]

6 months ago I got a explorer 96 4.0 ever since the thing was overheating the temperature rises then drops back to normal after a minute or so will happen every 7 minutes roughly..I was told the gauge was messed up when I got it was sitting for years but had always concerned me and I kept a eye on fluid level.no visible loss of coolant but have to add a gallon every time I drove it.one day on highway it got hot and I figured it would drop temperature but instead it started smoking so I pulled into gas station it was smoking from oil cap with milky residue on cap and smoke coming from radiator . It didn't turn over at first It turned back over after letting it cool adding fluids it ran horrible and I took it straight home parked it for 2 months or so.I changed the water pump and thermostat all fluids and still overheating.I got to point I wouldn't use it but for around the neighborhood for last couple months no more than couple miles it runs ok aside from over heating and puffs white smoke and consumes a lot of coolant/water..soo recently I got laid off and figured there was time to work on it and have stripped it to exposed cylinders here comes point I need advice..I want to replace the cylinder heads wth remanufactured heads change all gaskets on intake ect. But I have a few worries all parts for this project will cost me nearly what it's worth if I get 50k miles out of it I'm ok with that I know the heads need to be replaced but if I do al these repairs I'm afraid wow what if engine block itself is cracked making all my efforts in vain and $ wasted..I have had advice here and there but I seek more hence my presence here.for 2 weeks it has been stripped to bare engine cylinders exposed I've never been this deep in a engine but am confident I have no short comings in mech ability to pull apart put together what I have started. I received important council mentioning whatever caused it to overheat before heads cracked still exists so I'm going to purchase new radiator as we'll I'm just scared i am going to waste my $ how would I know If block is cracked since there has never been visible leak and no stains near freezer plugs and what are all components that could cause over heating.. Thanks for any advice sorry this is so long trying to be specific but please help if possible I want to get this beast back on road so I can pull my other truck apart.

 

[joe doe]

first off before you tore it down the overheating sounded like you needed a new rad cap .sounds silly but your rad cap is what keeps the coolant under pressure and from boiling .that would have been my first thing i tried .

now when you said the oil cap had milky residue and your using coolant thats a tell tale sign of a blown head gasket .that and the white smoke coming from the tailpipe . you should have checked your oil for signs of coolant in it .

anyway ,now you got it stripped down to the heads .its been awhile since i researched heads but the place to go use to be alabama cylinder heads ,now i hear they are under a different name ...http://www.promaxxperformance.com/

you could try them . or maybe you have your own source?

your on the right track .the explorer heads are known to crack between the valves ,look around the valves for cracks,thats where they crack and coolant gets by and into the cylinders .
do you have ohv engine?or ohc ?
in either event i would go with ford gaskets just tell them you need everything to do a cylinder head replacement .
head gaskets
intake gaskets
plenum gaskets(its a one piece staggered looking oring type gasket)
valve cover gaskets
new head bolts (you need new old cannot be reused)
if your that far into it ,oh wait you done a water pump already......but anyway if your that far into it i would go ahead and change out the timing chain cover gasket right away,if you have the overhead valve engine the coolant passage goes thru that cover and that can or will start leaking once you plug up the other leaks .
i had to do my head gaskets on my 2000 4.0 and after i done all that came to find out my timing chain cover was leaking coolant too. so had to do that after the fact .i have a 4.0 ohv engine .

if your head was cracked between a cylinder more than likely you would have been fouling plugs or getting cracked insulators on the plugs .you didnt mention if any codes were thrown??

if you have a ohv engine its a good engine and worth the repair if you didnt damage it. now if its a overhead cam engine ......well those have issues with timing chain cams and can be a real pita . if you have that engine and its high mileage i would consider getting a low mile replacement .

my 2000 4.0 ohv now has 165,000 on it and runs great still .doesnt leak a thing anymore or use any oil .its a good engine .
good luck and i will be back to check on you .dont forget a new rad cap!

ps- would have been easier to check the block for cracks before you tore it down .could have added a fluorescent dye to the coolant and looked for it on the block with a uv light after running it a bit .now you will just have to inspect it with a good light .i doubt your block is cracked unless you seriously overheated it and just kept driving .

another thing , no reason you cant reuse your heads long as they arent cracked .if it was just the head gaskets that went bad and no plugs ever fouled on you i would think they are ok .you could have a machine shop give them a look over and then decide .my heads came off and went back on . just all my gaskets were leaking

 

[joe doe]

heres what the cracks between a cylinder look like

this is the kinda thing you wanna look for .if you dont see any then no reason you cant reuse the old heads,you will have to remove all traces of old gasket material to find them .you will have to do this anyway

 

[Callmejohn]

I had checked the oil often and changed it a couple times in fear of contamination never have seen any discoloration on dipstick only the one time it badly overheated and was on oil cap head when it was smoking.i do have a pushrod engine as I was thinking of changing all the rods out too. A couple months back I checked it for codes and got 2 one was cylinder misfire or bad plug the other was sensor in exhaust . At least 2 if not 3 of my spark plugs cracked when I pulled them out 5/6 looked horrible there was coolant sitting on top of 4/6 cylinders after I removed the heads. I hope that answered the questions you had. I will look into this timing chain cover and radiator cap ASAP thank you very much for your input.. I think I will push forward

 

[joe doe]

cylinder misfire another sign of coolant getting in or just a bad plug . if you can remember what plug was misfiring that would give you a place to start looking for head cracks near that plug .
also look for cracks around the heads where there was coolant in the cylinders .that could happen from just bad head gaskets as well but doesnt hurt to look the head over in that area .

post your findings

ps- i meant timing chain cover gasket ,the covers are fine but the gasket can or will leak once you plug everything else up .